diff --git a/tools/quake3/q3map2/light_ydnar.c b/tools/quake3/q3map2/light_ydnar.c
index 4bfbd1da..d2d0f9da 100644
--- a/tools/quake3/q3map2/light_ydnar.c
+++ b/tools/quake3/q3map2/light_ydnar.c
@@ -2774,9 +2774,10 @@ void IlluminateVertexes( int num ){
    determines opaque brushes in the world and find sky shaders for sunlight calculations
  */
 
-void SetupBrushesFlags( int mask, int test )
+void SetupBrushesFlags( unsigned int mask_any, unsigned int test_any, unsigned int mask_all, unsigned int test_all )
 {
-	int i, j, b, compileFlags;
+	int i, j, b;
+	unsigned int compileFlags, allCompileFlags;
 	qboolean inside;
 	bspBrush_t      *brush;
 	bspBrushSide_t  *side;
@@ -2806,6 +2807,7 @@ void SetupBrushesFlags( int mask, int test )
 		/* check all sides */
 		inside = qtrue;
 		compileFlags = 0;
+		allCompileFlags = ~(0u);
 		for ( j = 0; j < brush->numSides && inside; j++ )
 		{
 			/* do bsp shader calculations */
@@ -2813,7 +2815,7 @@ void SetupBrushesFlags( int mask, int test )
 			shader = &bspShaders[ side->shaderNum ];
 
 			/* get shader info */
-			si = ShaderInfoForShader( shader->shader );
+			si = ShaderInfoForShaderNull( shader->shader );
 			if ( si == NULL ) {
 				continue;
 			}
@@ -2823,7 +2825,7 @@ void SetupBrushesFlags( int mask, int test )
 		}
 
 		/* determine if this brush is opaque to light */
-		if( (compileFlags & mask) == test )
+		if( (compileFlags & mask_any) == test_any && (allCompileFlags & mask_all) == test_all )
 		{
 			opaqueBrushes[ b >> 3 ] |= (1 << (b & 7));
 			numOpaqueBrushes++;
@@ -2836,7 +2838,7 @@ void SetupBrushesFlags( int mask, int test )
 }
 void SetupBrushes( void )
 {
-	SetupBrushesFlags(C_TRANSLUCENT, 0);
+	SetupBrushesFlags(C_TRANSLUCENT, 0, 0, 0);
 }
 
 
diff --git a/tools/quake3/q3map2/main.c b/tools/quake3/q3map2/main.c
index b1d5a547..6b85c3d2 100644
--- a/tools/quake3/q3map2/main.c
+++ b/tools/quake3/q3map2/main.c
@@ -389,7 +389,10 @@ determines solid non-sky brushes in the world
 
 void MiniMapSetupBrushes( void )
 {
-	SetupBrushesFlags(C_SOLID | C_SKY, C_SOLID);
+	SetupBrushesFlags(C_SOLID | C_SKY, C_SOLID, C_NODRAW, 0);
+		// at least one must be solid
+		// none may be sky
+		// not all may be nodraw
 }
 
 qboolean MiniMapEvaluateSampleOffsets(int *bestj, int *bestk, float *bestval)
@@ -744,20 +747,25 @@ int MiniMapBSPMain( int argc, char **argv )
 				if(v > ma)
 					ma = v;
 			}
-		s = 1 / (ma - mi);
-		o = mi / (ma - mi);
+		if(ma > mi)
+		{
+			s = 1 / (ma - mi);
+			o = mi / (ma - mi);
 
-		// equations:
-		//   brightness + contrast * v
-		// after autolevel:
-		//   brightness + contrast * (v * s - o)
-		// =
-		//   (brightness - contrast * o) + (contrast * s) * v
-		minimap.brightness = minimap.brightness - minimap.contrast * o;
-		minimap.contrast *= s;
+			// equations:
+			//   brightness + contrast * v
+			// after autolevel:
+			//   brightness + contrast * (v * s - o)
+			// =
+			//   (brightness - contrast * o) + (contrast * s) * v
+			minimap.brightness = minimap.brightness - minimap.contrast * o;
+			minimap.contrast *= s;
 
-		Sys_Printf( "Auto level: Brightness changed to %f\n", minimap.brightness );
-		Sys_Printf( "Auto level: Contrast changed to %f\n", minimap.contrast );
+			Sys_Printf( "Auto level: Brightness changed to %f\n", minimap.brightness );
+			Sys_Printf( "Auto level: Contrast changed to %f\n", minimap.contrast );
+		}
+		else
+			Sys_Printf( "Auto level: failed because all pixels are the same value\n" );
 	}
 
 	if(minimap.brightness != 0 || minimap.contrast != 1)
diff --git a/tools/quake3/q3map2/q3map2.h b/tools/quake3/q3map2/q3map2.h
index 08e9b1c8..ffb056ab 100644
--- a/tools/quake3/q3map2/q3map2.h
+++ b/tools/quake3/q3map2/q3map2.h
@@ -1764,7 +1764,7 @@ void                        DirtyRawLightmap( int num );
 void                        IlluminateRawLightmap( int num );
 void                        IlluminateVertexes( int num );
 
-void						SetupBrushesFlags( int mask, int test );
+void						SetupBrushesFlags( int mask_any, int test_any, int mask_all, int test_all );
 void                        SetupBrushes( void );
 void                        SetupClusters( void );
 qboolean                    ClusterVisible( int a, int b );
@@ -1820,6 +1820,7 @@ void                        EmitVertexRemapShader( char *from, char *to );
 
 void                        LoadShaderInfo( void );
 shaderInfo_t                *ShaderInfoForShader( const char *shader );
+shaderInfo_t				*ShaderInfoForShaderNull( const char *shader );
 
 
 /* bspfile_abstract.c */
diff --git a/tools/quake3/q3map2/shaders.c b/tools/quake3/q3map2/shaders.c
index 153f3daa..dfbc7f19 100644
--- a/tools/quake3/q3map2/shaders.c
+++ b/tools/quake3/q3map2/shaders.c
@@ -801,6 +801,12 @@ static void LoadShaderImages( shaderInfo_t *si ){
    finds a shaderinfo for a named shader
  */
 
+shaderInfo_t *ShaderInfoForShaderNull( const char *shaderName ){
+	if(!strcmp(shaderName, "noshader"))
+		return NULL;
+	return ShaderInfoForShader(shaderName);
+}
+
 shaderInfo_t *ShaderInfoForShader( const char *shaderName ){
 	int i;
 	shaderInfo_t    *si;